Reproduction process



sept. so, 1941. o, F WOOD 2,257,143

REPRODUCTION PROCESS File'd May 23, 1938 v :gli 61 66g 68 52 WMWMW/IM 5g 1:1'15' INVENTOR 55 0623.917 Woa BY f 54 57 AT RNEY Patented Sept. 30, 1941 UNITED STATES PATENT OFFICE 2,257,143 v REPRODUCTION PROCESS om F'. wood, New York, N. Y. Application May 23. 1938, Serial No. 209,468 7 claims. (cl. @i1- 25) The present invention is directed to methods of reproduction and is particularly directed to methods of making printing plates.

It has been customary to preparecuts and plates for printing purposes, whether for flat printing, as for example, in the case of books, or for relief printing, intaglio printing, cylinder printing, as for example, in the case of newspapers and magazines, by etching certain portions of a metal plate or cylinder with various acids.

The production of these printing plates or rollers necessitates the employment of photographers, photo-engravers, electro-typers and e usually it is necessary to transfer the material from one group of workers to another and sometimes even from one shop to another or from one department to another before the final plate or cylinder is obtained, to which ink could be applied and from which the ink might be transferred to the paper or other stock which was to be printed.

These repeated handlings and transfers between different departments and from one group of workers to another not only resulted in conslderable delay, but also Lsubstantially increased the cost of manufacture and in addition a great deal of time had to be spent in nishing, cutting away or routing the final cuts or plates with large amounts of wastematerials.

Moreover it was frequently necessary to produce negative plates which had to be transferred into positive plates and various stereotype processes had to be utilized to obtain plates suitable for cylindrical or roller printing from the nat etchings which were initially produced.

Furthermore, considerable difficulty was experienced inthe etching, requiring re-touching and expensive, and time consuming manual labor to obtain the proper depth and character of plate after the etching had been completed and it was not possible readily to gauge the depth of the etch or to control it in such a way as to auto` matically determine the depth of the various etches or character of the recesses formed therein.

It is among the objects of the presentinvention to provide an improved method of reproduction and of producing printingplates of the character above described in which by relativelyinexpensive, rapid and simple methods, it will 'be possible to obtain reproductions or to obtain printing plates, either for flat or cylindrical printing,

rate control-at all times by the operator or person in technical control of the printing processes in the printing establishment.

Another object is to provide an improved process for producing printing and other reproduction plates which will eliminate the necessity of makllng repeated negative and/or positiveplates.

which will eliminate most of the touching up, routing or manual labor which is necessary in the manufacture of printing plates of the present day and which will further eliminate the necessity of utilizing several shops or departments or dlierent groups of workers before the nal plate is produced with the resultant increased cost and delay.

Other objects vwill be obvious or will become apparent during the course of the following specil ilcation.

In accomplishing the above objects the object to be reproduced or the picture to be reproduced is directly photographed upon a sensitive emulsion carried by the element, 'which is to be etched by the etching agent, whether the etching agent be water or an organic solvent or an acid.

The plate to be etched may consist of a laminated structure including thin closely adherent layers of various metals, such as aluminum, copper, iron, tin, zinc, chromium and so forth; and/ or of various synthetic plastic materials with pigments and/or fillers, such as vlnylite resins,

acrylic acid resins, rubber, phenol formaldehyde resins, styrene or styrol resins, urea formaldehyde resins, casein materials, natural resins as gum dammar, shellac, manila gum, rosin and gum accroides, phthalic acid-glycerol resins, and cellulose derivatives, such'as cellulose nitrate, acetate or ethyl cellulose and so forth; and/or inorganic materials, such as wood, paper. glass, asbestos, 'combinations of wood hour, silica dust, magnesium oxide, calcium carbonate, barium sulphate or othei` insoluble inorganic salts, oxides, or pigments with-flour, sugar, dextrin, sterol, arabic, water glass, gum tragacanth, gum shirez, water soluble cellulose ethers and so forth as binders. The fillers or pigments above mentioned may consist of ground ceramics, powdered chalk, powdered barium sulphate, white lead, clay, iron oxides, insoluble organic ago dyes, lacs, chrome green or yellow, Prussian blue, lithopone, plaster of Paris, aluminum oxide and so forth.

Thel top or upper layer or an intermediate layer may be sensitized and may consist of various which will reproduce accurately the character E and texture of the object or picture to be printed and which, at thejsame time, will be vunder accueombinations of colloids, such as glue, gelatin,

albumen, Egyptian bitumen, and so forth, containing a substance acting as an insolubilizing agent upon exposure to light such as a bichrom-ate.

Although these laminated plates may be formed 1 in many different ways by adhesion or spraying or painting the various materials upon a base, it is possible to form them by electrical deposition of diiferent metals from diierent baths containing dissolved salts of the metals or from the same bath with the deposition being controlled` by variation in the deposition potential.

'Ihis is Aparticularly useful in forming laminated plates which may Ycontain copper, iron, tin, zinc and other metals of this character.

If desired, the electrolytic baths may also be utilized' to depose the nally divided suspensions 15 of the resins or cellulose esters or even ilnally divided rubber inthe form of latex.

In addition to depositing by electrolysis or electro-phoresis, it is also possible to deposit the layers of etchable metals, resins or other mate'- 20 rlals, by spraying, coating or in other suitable fashions. The thickness of the individual layers may vary from a. fraction of a thousandth of an inch up to several thousandths of an inch.

if desired, depending upon the particular form 25 which is to be produced. Y

It is to be, however, understood that the present invention is also applicable in many respects to plates which are of one metal or of one material.

In carrying out the present invention the plate, which may be of laminated or unlamnated structure, is coated with the light sensitive gelatin material and then is exposed in a frame to direct sunlight passingthrough a picture or sketch `to be reproduced or may be placed in a photographic camera or other apparatus and directly exposed. Y A a After exposure for the desired length of time,

that portion of the gelatin which has been acted 40 upon by the light will become insolubilized, while the remaining portions remainy soluble and `may be rubbed, brushed or sponged oit or otherwise removed Afrom the plate.

It is also possible, of course,V instead of using Y combinations of gelatin and bichromate, to use `'other protein or colloid combinations which.

`upon exposure to light j or treatment with a chemically active drawing lnk or crayon, will undergo chemical be reproduced, while other portions will remain unaffected.

In such Acase a special ink or material may be rubbed over orY applied to the surface of the treated 'colloid to Vail'ect those portions which 1 have been changed so as to protect them or inisolubilize them while the remaining portions may be suitably'removed by'solution, by. brushing or by other methods. Present photographic and/or engraving methods may o f course be utilized insofar as they are applicable to the present invention.

l For example to a gelatin layer containing suitable iron salts, a drawing in a chemically active ink or crayon maybe directly applied without exposure to light.V At portions corresponding to the crayon or lines of Ythese drawings, there will be insoluble depositsl formed in the gelatin,

which insoluble deposits will insolubilize the gelatin upon ,subsequent treatment or will protect the metal beneath the gelatin, as the case may ',be. Othercifsetting, transferring or printing -processesinay also be employed.

Afterthe unaffected protein or gelatin or other Y changes-in certain aiected 50 portions, col'lespndingfto a picture or design to been completed.

colloid has been removed, exposing the metal or other material forming the top surface of the printing plate, an etching material is applied.

For example, where glass is the surfacing of the plate, hydrofluoric acid may be used as an etching material.

With ccllulosic materials, as paper or regenerated cellulose films, strong nitric or hydrochloric acids may be used as etching agents, as may also salts, and as zinc chloride, followed by drying and/or heating.

Where aluminum or zinc are employed, different concentrations of caustic soda or caustic potash may be employed.

With diierent metals, such as copper, iron, diil'erent acids or `salts may be employed, such as nitric, sulphuric, phosphoric, acetic, iron trichloride and so forth.

Dilute acids will attack some metals and con'- centrated acids will attack others, while combinations of acids will attack still others and advantage may be taken of the speciilc or selective action of different acids in diierent concentrations and mixtures upon different materials.

With cellulose esters or resins or rubber as a surface or intermediate layer upon a laminated plate, organic solvents may be employed, such as acetone, benzene, ethyl acetate, various methyl, ethyl, propyl, butyl, amy] hexyl or estersl tions, it is possible after etching entirely through one layer or lamination to protect portions of the exposed next lamination and then etch through the next lamination in places 'or all over, if dei sired, by another solvent or a diilerent concentration of the same solvent.

By the use of laminated plates, it is possiblev 'I'hese transparent laminations may be formed.

of glass or of synthetic resins, or of rubber or even of cellulose esters or regenerated cellulose On the other hand where copper is the facing layer and iron is the next lamination, if the iron sheet is polished, upon etching through the copper layer with sulphuric a.cid, the silver nish of the iron plate will immediately ilash out when the etching is complete.

Where' the bottom laminations are of transparent or translucent material, alight may also be placed below the plate, which light will shine vthrough the plate as soon as the etching has In this manner it is possible most readily to prevent undercutting and to control the depth of the etching and the character thereof so as to give a proper finish to the edges of the removed portions which will be o! value in connection with the formation of the ilnal printing plate from the etched plate. When the castings are made, the bottom of the etching becomes the top of the printing plate and the sides of the etched out portions will become the sides oi' the relief on the printing plate.

On topof the metal plates and below the photographically sensitive emulsion there may also be placed water soluble compositions, such as combinations of various water soluble gums or dextrlns above mentioned and calcium carbonate, barium sulphate, insoluble inorganic salts, insoluble organic or inorganic lakes and pigments and so forth. v

In this connection, these materials may be made in different layers and of different solubilities, as for example, by using different binders which will not all be affected by water or by water vof the same temperature or by water containing certain dissolved salts.

For example, where pectln is a binder, a water alcohol mixture may be utilized which will not dissolve the pectin', while with certain types o f cellulose derivatives or Vgums or synthetic resins or even gelatin, agents may be included which will prevent solution or on the other hand insolubilize partly or wholly the water soluble binder material.

During the process of etching it is necessary, of course, to protect the portions which are not to be etched and many suitable resistance inks may be applied to the gelatin portions which have not been removed, which will prevent any action ,of the etching solvent or liquid at these places.

When the etched plate has been finally produced the protection materials,`whether they be varnishes or gelatin or other materials, are then removed and from the intaglio plate which is thus produced there may be formed or case the positive printing plate, either by casting metal thereon with the intaglio element in flat or curved condition or by pressing resin, rubber or other plastic materials thereon to obtain the desired reproduction of the etched portions.

This printing plate which is produced from the matrix, either in resin or metal or in plastic materials in flat or curved condition and which may be Vdirectly employed for printing purposes will.` 'give a faithful and clear reproduction of the original object or picture which is to be reproduced. Y

'I'he process just described produces a negativev matrix and a positive printing plate therefrom, but if desired a positive matrix may be produced in the ilrst instance, which matrix may be used directly as a printing plate, or a negative printing plate may be obtained therefrom by impression or casting.

The latter may be done by removing the .portions of the gelatin which have not been insolubillzed and then filling the space left by these removed portions with a protecting material, such as a varnish, powdered resin or some other similar material which will prevent etching at these particular portions. Then the remaining insolubilized gelatin may be removed, exposing the metal or other surface of the plate which then may be etched by water, organic solvents, acids, alkalies, or other materials.

Where a special grain is to be obtained, the

plate may consist'of or be covered or laminated f with selected alloys containing carbon which will have the eiectof causing a grain of the plate.

Among the protecting materials which may be utilized are inks, waxes, bitumen, dragons blood, various varnishes or lacquers and so forth and in general materials inert toward a non-soluble in the etching materials, waxes, such as paraffin,

beeswax, carnauba wax, Japan wax and ceresin wax will protect against acids, alkalies and water, and drying oils or varnishes or inks containing the same will give similar protection.

In some cases it may even be desirable to build up the plate and in such a case, those portions in which the solubilized gelatin has been removed or in which the insolubilized gelatin isfremoved may be electroplated with a protecting material, such as chromiumnor where the exposed face is not of metal, such face may be covered with, carbon, which in turn may be electroplated or subjected to electrophoresis.

Although many different etching materials may be 4utilizedjor the metals for copper, it has been found most suitable to utilize solutions* of ferrie chloride having a concentration of 37 to 45 B.

With zinc, nitric acid has been found to work quite satisfactorily, while with aluminum 10%A caustic soda is quite effective.

In case of laminated plates of zinc and aluminum zinc is decomposed by nitric and sulphuric acid, while these acids in concentrated condition do not affect aluminum.

As protecting or binding agents, it is possible -to use various inks, Venice turpentine, glycerol,

waxes such as paraiiln, beeswax: carnauba wax, Montan wax and so forth, linseed oil, rapeseed oil and/or various resins. Asphalt and shellac varnishes have also been found quite satisfactory. These materials may also be used as binders or ingredients of the laminated structure.

As4 light sensitive emulsion, itv is possible to use combinations of albumen, gelatin or fish glue,

together with ammonium bichromate and aqua ammonia.

Referring to the `drawing which illustrates diagrammatically by way of example one possible method of carrying out the present invention,

but to which the invention is by no means restricted.

Fig. 1 shows an exposed plate.

Fig. 2 shows the metal vplate or combination b pailn; having a laminated structure, as indicated a Fig. 3 is a perspective view illustrating how the plate may be examined or inspected from a light source.

Fig. 4 illustrates in perspective a final cast printing plate,

Fig. 5 illustrates diagrammatically in cross section a laminated sensitized plate with the various laminations thereof separated,

Fig. `6 represents the same plate with the inatlons together,

Figs. 7 to 16 illustrate diagrammatically in cross section the various steps in the process of utilizing the sensitized plate.

The plate shown in Fig. l has been exposed in a camera. The light passing through the lens strikes the gelatin surfacing i2 on Fig. 2, insolubilizing portions thereof as indicated at Il and leaving portions indicated at I4 unaffected. As

lam-

.a result the portions' Il, may be removed by brushing or sponging or by solution andthe exposed insolubilized portions I3 may be covered with an ink or other protective material to prevent etching thereof.

The plate, as indicated in Fig. 5, may consist oi' the sensitized gelatin layer I2, a metal or some other composition I5 and a contrasting metal or some other composition or even a transparent or translucent layer I6. The three plates or layers may be assembled either by direct coating processes or by electro-deposition or electro-phoresis methods.

In Fig. 7 it will be noted that the emulsion is removed from the unexposed portions at I4 and stays in position at the exposed portions I3 where it may be coated with a suitable ink or protective material. A

When the upper lamination I5 is then treated with an etching material, such etched material will eat into it as indicated at I1 in Fig. 8. As indicated at I1, the etching has not taken place to the full depth of the layer I5. Where the etching is carried out to the full depth, the metal or contrasting material forming the lowermost lamination I6 will immediately ash out and be visible.

Where the lowermost layer is transparent the plate may be examined or inspected by a light source II shown in Fig. 3 to determine the progress of etching through the upper layer.

In the alternative procedure illustrated in Figs. 9 to 11, in the portions I4 from which the emulsion has been removed, is placed a protecting resin or material I9, as indicated in Fig. 10, and then the insolubilized gelatin at I3 is removed.

'Ihen an etching agent is added, with the result that the metal or other, surface will be removed, as indicated at 20, while the portions I4 will remain unaiected. Finally, the resin I9 in Fig. 11 or the/gelatin I3 in Fig. 8 may be removed and a cast made with resin or som other plastic material or with molten metal. The molten metal may be any suitable low melting point alloy including antimony, lead,v zinc, tin, bismuth, cadmium and so forth. Stereotype metals having melting points ranging from 275 to 400 C. are very suitable.

'Ihis cast printing plate as indicated in Fig. fi will reproduce the original object or picture shown inFig. 1 with the metal or resin or other plastic material being relatively elevated at 2| as compared to 22, when the procedure of Figs. 7

` and 8 is employed, or reversely when the procedure of Figs. 9 to 11 is employed.

In Fig. 12 a laminated structure is shown which includes an upper light sensitive layer 50, an intermediate metal layer 5| and an intermediate light sensitive layer52 and a backing layer 63 of glass or other transparent or translucent materials.

With the construction of Fig. 12, the light seni sitive layer 60 may be exposed in a camera,

treated to remove the unaffected material, then directly etched as indicated in Fig. 8 or reversely etched by using the process indicated in Fig. 11.

The light sensitive layer 52 in the meanwhile may be exposed through the glass or transparent radiation, the intermediate light sensitive layers 56 and the central layer 51. vThe central layer 51 may be of a material, such as lead, which cannot be penetrated by various forms of radiation above mentioned.

A suitable exposure on' one or both sides followed etching or processing in the manner disclosed in Figs. 8 and 11, will result in the production of complementary or supplementary plates or matrices on opposite sides of the central supporting plate 51.

Figs. 14, 15 and 16 shown an alternative process according to which a plate 60 of metal or resin or of laminated construction, as indicated in Figs. 5 to 11, may be grained by etching, as indicated at 6I. Then thevungrained portions 62 may be built up, as indicated at 63, by mixtures of plaster of Paris and binders, plastic clays, or combinations of other iiller materials. Then the casting or impression, indicated at 64, may be made with the result that the portions at formed in the recess 66 and having the grain surface 61 will project substantially above the other portions 68 of the plate 64.

The amount of relief may be readily varied by utilizing various heights of Afiller 63 upon the portions of the matrix outside of the portions have been grained or etched, as the case may be. Instead of utilizing a light sensitive upper layer, in-

cluding gelatin, glue or albumen and a bichrolacid or hydrochloric acid, or by means of certain metallic salts, such as zinc chloride.

A drawing or writing may be formed upon the paper by means of the etching material and as a result the portion of the paper upon which the drawing or writing has been made, when dried and/or heated, may be rubbed out, dusted away orAotherWise removed. The thickness of the paper may be controlled 'so as to give a desired depth to the plate, which may then be formed by impression from the printing plate.

It is also possible to wax orrotherwise treat portions of a layer or surfacing consisting of paper or other cellulosic material which is ordinarily subject to disintegration by water or by rub away or cause disintegration of the untreated back 53 or by exposure to a source of light which will penetrate the copper metal or plastic layer 5I, such as for example radiations from radioactive material or X-rays. Y

This treatment may result in a grain being formed upon the bottom of the etched out portions in the copper layer 5I and such grain will form the top of the printing plate' which may be cast or formed tcm the laminated plate of Fig. 12.

In Fig. 13 is shown a double laminated plate.'

having the outside .light sensitive layer 54, the

intermediate layer or plastic layers 55 which may be penetrated by X-rays or other forms of .places from the action of portions of paper or other materials. "Wax and resins may also be utilized directly upon metals to .protect these metals in certain With resinous layers orV layers of plastic materials, drawings or sketches orother protection may be applied thereto. Which will not be affected by the organic solvents, which are utilized to dissolve, remove or cause disintegration of the resin or plastic material, as the case may be.

. Furthermore one or more of the laminations, either the top lamination or the lamination next below the light sensitive gelatin or glue coating.

. may be made of a composition of an inorganic material and an organicmateri'al, such as for example, combinations 'of materials as powdered resin, rubber or other lplastics above described etching agents, what- Aever their nature maybe.

and inorganic materials, as chalk, clay, bauxite, ground ceramics, ground `silica and so forth.

. In this instance, when the gelatin coating is removed in those places, where it has not been insolubilized, treatment with a solvent or softener for the finally divided materials in #the lamination will cause them to bind together.

For example, with a mixture of powdered resin and chalk, alcohol may be used to soften or cause a conglomeration or adhesion of the mixture of powdered resin and chalk.

Where the mixture consists of powdered sugar or other powdered or some other inert filler, water will be suiiicient to cause the adhesion. Then upon removal of the insolubilized gelatin or other insolubilized material which has been protecting the residual surface, such residual material may be readily dissolved or disintegrated and removed, leaving only that portion of the lamination which has been caused to cohere or coalesce by reason of the action or absorption of the sol- .vent or liquid reagent.

The etching material, of course, may be drawn by stylus, brush or pencil upon metal, resin or other types of upper laminations in lieu of or in addition to exposing such laminations to the acl tion of light in a camera.

Among the other resinous materials which may `be utilized in lieu of those mentioned above are the copals. Gum mastic, kauri gum, pitch and so forth may be used. In addition to the above waxes there may also be utilized as binders or as protectors ceresin, Japan wax, ozocerite and marble Wax.

Many different types of saturatedand unsaturated oils or fats may also be utilized either as protectors or binders such as castor oil, China nut oil, cocoa fat, tallow, cocoanut oil, Neets foot oil, corn pil, cottonseed oil, fish oils, animal oils, such as lard, seal, tallow, whale, oleo, and the like, paraine oil, and various vegetable oils, such as wood oil', peanut'oil, pine oil, rapeseed oil, red oil, rosin oil, sesame oil, soyabean oil, tar oil and so forth.

As pigments and/or fillers there may also lbe gold bronze, silver bronze, aluminum powder, casein powder, ultramarine blue, chrome blue, lamp black, bone black, titanium oxide, Vermilion red and cadmium selenide. These pigments may be used as fillers or as pigments only and they may be combined with or substituted to by various materials, such as zinc oxide, stearate of zinc, Whiting and so forth;

Many types of solvents, of course, may be emi ployed, such as the various carbitols, carboiwlic esters, as ethyl, methyl, butyl, propyl, amyl acetates, formates, succinates, phthalates, benzoates, lactates and so forth, toluol, benzol, xylols, acetone and so forth. Carbon tetrachloride, chloroform and dichiorethylene and other chlorinated or halogenated aliphatic or aromatic hydrocarbons have also been found valuable in certain connections.

As water soluble binders, it is possible to utilize water glass, tapiocastarch, sweetpotato starch, British gum, molasses or honey, whereas tung oil, olive oil, lemon oil, lavender and other similar oils may be utilized both as binders, protectors, absorbents or coherers Where castings are made from readily molten materials, it is possible by an electric heating iron to melt the metal directlyl on the face of the matrix or grained or etched plate. K

Where rubber is utilized to lform the 'laminations or more preferably to form the impressing or molding material, it is usually found most desirable to use a self-vulcanizing rubber.

Where cellulose acetate is used as the facing layer of a laminated plate, it is readily possible carbonate or plastic clay with suitable binders, a

pen knife may readily be utilized to scrape away or correct the etched portions without the necessity of utilizing metal working tools and the matrix thus may be readily corrected without routing.

' It is obvious, of course, that either the, matrix or the impression made therefrom may constitute the negative or positive printing plate and that many variations may be made in the materials employed.

The present procedure simplifies methods of making engravings, etchings, matrices and printing plates by providing compositions and metals which are easily and rapidly etched by cheap solvents and acids which do not require expert manipulations as are required by present procedures. It eliminates the making of photographic positives and much of the time now required in making matrices and printing plates, and in addition it makes it possible to make cheap duplicates or reproductions of original engravings and it also eliminates the costly and timeconsuming routing processes whichmust be conducted upon unetched metal and which cause serious Waste of metal in most printing estabpossible for a printing establishment by the use.

of its own labor without the need of skilled workmen to readily produce within a short period the necessary reproductions to be incorporated in the final printed materials.

Itis thus apparent that the present applicant has provided an improved reproduction process which may be widely employed in printing procedures and which is of great value in reproduction processes.

' 'I'he invention, however, is not intended to be restricted to any particular construction or arrangement of reproduction plate, or to any particular application of any such construction, or to any specific method of operation, or manner of use, or toany of various details thereof, herein shown and described, since it may be applied to the production of all types of relief or intaglio matrices or printing plates and the same may be modified in various particulars orbe applied in many varied relations without departing from the spirit and scope of the claimed invention, the practical embodiments herein illustratedand described merely showing some of the various features entering into the application of the invention.

2. A process of making a matrix or a printing plate comprising providing a transparent base,

, placing a photographically sensitive coating -on 3 said base, then placing a non-photographically `sensitive coating on said sensitive coating, and

then iinally placing another photographically sensitive coating on said last-mentioned coating, `exposing the coatings, removing parts of the plate comprising providing'a transparent base,

placing a photographioally sensitive coating'on `said base, then placing a non-photographically `sensitive coating on said sensitive coating, and `then nally placing another photographically sensitive coating on said last-mentioned coating,

`exposing the coatings, removing parts of the coatings which have been differentiated from the other part of the coating by the light, etching the base where the coatings have been removed,

and then making an impression of the base to `form the plate with a plastic resin.

4. A process of making a matrix or a printing `plate comprising providing a transparent base,

placing a photographically sensitive coating on said base, then placing a non-photographically `sensitive coating on said sensitive coating, and

then iinally placing another photographically sensitive coating on said last-mentioned coating,

exposing the coatings, removing the parts of the coatings unaffected by the exposure, protecting the remainder of the coating, etching the base where the coatings have been removed and then making an impression of the base to form the plate.

5. For use in a process of making a matrix or printing plate, a reproduction plate comprising a base capable of being etched and a light sensitized protein coating thereon; said base consistingv of a plurality of metals capable of being etched by an acid and the lowermost layer of said base being transparent and being coated by a thin coating of a photographicaily sensitive material.

6. For use in a process of making a matrix or printing plate, a reproduction plate comprising a base capable of being etched and a light sensitized protein coating thereon, said base consisting of a laminated structure of metals of contrasting color and solubility and the vlowermost layer of said base being transparent and being coated by a thin coating of a photographicallysensitive material.

7. For use in a. process of making a matrix or printing plate, a laminated reproduction plate to be etched to form a printing plate or a matrix for a. printing plate comprising, a transparent bottom layer, a glue-bichromate top layer, a copper layer nextto the'top-layer and a gluebichromate layer between the bottom layer and the copper layer.

OTIS F. WOOD. 

